Machining tool



Patented July 29, 1941 UNITED STATES PATENT OFFICE MACHINING TOOL Karl Schriit'er, Berlin-Lichtenberg, and Walther Dawihl, Berlin-Kohlhasenbruck, Germany, assignors to General Electric Company, a corporation of New York No Drawing. Application September 3, 1938; Se-

rial No. 228,452, 1937 3 Claims.

This invention relates to machining. tools, in particular those intended for machining insulating material.

In machining insulating material, for example cutting, turning; drilling, planing, milling and the like, tools frequently are used the operative part of which consists either of oxides only, for example aluminum oxide and magnesium oxide 'in connection with siiicic acid or of mixtures of oxides with metallic binders, for example of aluminum oxide with iron. Furthermore, tools frequently are used in which oxides constitute the binder for other hard material, such as silicon carbide. Serious difliculties are encountered in many cases in fixing such oxiceramic or oxiceramically bound tool tips to a tool shank consisting of steel or any other suitable metal, be

cause the solders generally used with hard metal tools and consisting of copper, brass or bronze do not give a firm bond with oxiceramic or oxiceramically bound tool tips. For this reason any additional mechanical fastening means always had to be provided.

The present invention has for its object a very simple but very solid connection between a metal .lic shank and tips which substantially or en- Borax Per cent by weight 40 Germany September 6,

This mixture is melted and subsequently ground. The place of-junction on the tool shank is then painted with the paste thus obtained and when the paste has dried, the tip to be fixed suchas a cutting tip, is put thereonto, whereupon the whole is heated a short time, say some minutes, at a temperature of about 850 C. The I glass solder fuses at this temperature and firmly connects the shank with the tip.

When the coefiicient of expansion of the tip difiers too much from that of the shank material, one or more glass layers may be provided between the glass solder applied to the shank and the tip, the coefiicients of expansion of which glass layers lie between that of the glass solder and o; the tip.

What we claim and desire to secure by Letters Patent is:

1. A tool of the type described comprising a metallic shank and a tip prepared at least mainly of oxides or containing oxides as binder, said tip being fixed to the shank by means of a'glass solder containing at least one. of the following oxides: cobalt oxide, nickel oxide, manganese oxide.

2. A tool as specified in claim 1, in which between the shank and the glass solder applied thereto is provided at least one glass layer the coefflcient of expansion of which lies between that ofthe shank and of the tip.

tip which consists principally of one or more 'oxides, means for securing the tip to the shank, said means consisting 01. a glass solder containing one or more oxides from the group, cobalt oxide, nickel oxide andmanganese oxide.

KARL scnno'rnn. I wALTnrm Dnwnm Quartz l 25 Feldspar 25 Sodium carbonate 6 Potassium nitrate--. 3 4 Cobalt oxide I 0.5 Nickel oxide 0.5

3. In a tool comprising a shank anda cutting 

